Implementation of Distributed Generation with Solar Plants in a 132kV … · 2020. 6. 25. · Research Article Implementation of Distributed Generation with Solar Plants in a 132kV

Research ArticleImplementation of Distributed Generation with Solar Plants in a132kV Grid Station at Layyah Using ETAP

Ghulam Mujtaba,1 Zeeshan Rashid ,1 Farhana Umer,1 Shadi Khan Baloch ,2

G. Amjad Hussain,3 and Muhammad Usman Haider4

1Department of Electrical Engineering, The Islamia University of Bahawalpur, 63100 Bahawalpur, Pakistan2Department of Mechatronics Engineering, Mehran University of Engineering and Technology, 76062 Jamshoro, Pakistan3Department of Electrical Engineering, College of Arts and Sciences, American University of Kuwait, Safat, Kuwait4Department of Electrical Engineering, Electrobuild Engineering Private Limited, 39350 Sheikhupura, Pakistan

Correspondence should be addressed to Zeeshan Rashid; [email protected]

Received 11 January 2020; Revised 16 May 2020; Accepted 6 June 2020; Published 25 June 2020

Academic Editor: Raúl Gregor

Copyright © 2020 Ghulam Mujtaba et al. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work isproperly cited.

Decentralized power generation efficaciously merges technological advances in a rapidly changing face of power networksintroducing new power system components, advanced control, renewable sources, elegant communication, and web technologypaving the way for the so called smart grids. Distributed generation technology lies at the intersection point of power systems,power electronics, control engineering, renewable energy, and communication systems which are not mutually exclusivesubjects. Key features of renewable integration in a distribution network include loss minimization, voltage stability, powerquality improvement, and low-cost consumption resulting from abundant natural resources such as solar or wind energy. In thisresearch work, a case study has been carried out at a 132 kV grid station of Layyah, Pakistan, which has active losses, reactivelosses, low power factor, low voltage on the demand side, and overloaded transformers and distribution lines. As a result, poweroutage issue is frequent on the consumer side. To overcome this issue, a simulation of load flow of this system is performedusing the Newton-Raphson method due to its less computational time, fewer iterations, fast convergence, and independencefrom slack bus selection. It finds the harsh condition in which there were 23 overloaded transformers, 38 overloadeddistribution lines, poor voltage profile, and low power factor at the demand side. There is a deficit of 24MW in the wholesystem along with 4.58MW active and 12.30MVAR reactive power losses. To remove power deficiency, distributed generationusing solar plants is introduced to an 11 kV distribution system with a total of 24 units with each unit having a capacity of1MW. Consequently, active and reactive power losses are reduced to 0.548MW and 0.834MVAR, respectively. Furthermore,the voltage profile improves, the power factor enhances, and the line losses reduce to a great extent. Finally, overloadedtransformers and distribution lines also return to normal working conditions.

1. Introduction

The global emerging trend of deregulated electricity markethas underpinned a remarkable stride in the paradigm ofdistributed or dispersed generation (DG) by the use ofsmall photovoltaic or wind plants to cope with the inevita-ble shortcomings such as power outage, poor quality, volt-age regulation, and increased component losses incommercial and domestic infrastructure [1, 2]. These smallpower plants installed at subsequent stations not only pro-

vide better services to the consumers as backup sourcesbut also eliminate pollution, greenhouse gas emission, andglobal warming [3]. DG ranging from a few kW to MW isnow part of distributed energy resources which includesresponsive loads and energy storage [4]. It also reduces theneed for the distribution and transmission expansion withthe essential requirements of huge power plants [5]. Themost attractive prospect lies in the fact that DG is installedaround the network that is close to the consumer’s side tominimize power losses and voltage drops [6].

HindawiInternational Journal of PhotoenergyVolume 2020, Article ID 6574659, 14 pageshttps://doi.org/10.1155/2020/6574659

https://orcid.org/0000-0002-5592-4126https://orcid.org/0000-0002-7318-4715https://creativecommons.org/licenses/by/4.0/https://creativecommons.org/licenses/by/4.0/https://doi.org/10.1155/2020/6574659

The implementation of DG by renewable energyresources is advantageous in rural areas specifically to stabi-lize the power grid and ensure reliability at reduced cost ofgeneration and distribution [7, 8]. In order to exploit the fullpotential of DG, versatile and competent work force isrequired to cope with the broad spectrum of technical chal-lenges. Few of the associated issues hindering the robustoperation are the requirements of decentralized control [9],optimal placement of plants [3, 10], fault location [11], distri-bution system protection [12], reconfiguration [13], andintegration [14].

The last decade has been dedicated to the implementa-tion of the DG framework to furnish its overwhelmingfeatures to the power system community such as voltagestability and loss minimization [15]. Injeti and Kumaranalytically determined the placement and sizing of DGfor planning and operation of active distribution networksusing fuzzy logic [16]. They carried out a detailed perfor-mance analysis on 12-bus, 33-bus, and 69-bus radial distri-bution networks to conclude an enhanced voltage stabilityfactor at minimum losses. Mehta et al. proposed a selec-tion scheme of the best type of DG unit and its optimallocation by analyzing the voltage sensitivity index andbus participation factors using a power flow algorithmand modal analysis technique [17]. With these protocols,they were able to enhance the voltage stability of the distribu-tion network with simultaneous improvement in the voltageprofile for the 33- and 136-node radial distribution network.Onlam et al. proposed a novel optimization technique calledthe adaptive shuffled frog-leaping algorithm to solve the net-work reconfiguration and DG placement problems in IEEE33- and 69-bus distribution systems [18]. They definedspecific objective functions taking into account power lossminimization and voltage stability index improvement(VSI) and concluded that the power loss and VSI providedby this algorithm were better than all other protocols inboth 33- and 69-bus systems. Rudresha et al. presented amethod to determine the proper size and location of DGin a distribution system to reduce the losses and improvethe voltage stability for different loading conditions [19].They considered the IEEE 33-bus system to simulate thevoltage profile and losses in the system and concluded thatproper placement and sizing of DG potentially reduce thelosses, improve the voltage profile, and thereby improvethe voltage stability.

This paper deals with a comprehensive investigation of a132 kV grid station in Layyah, a backward city surrounded bydeserts in the southern part of Punjab Province in Pakistan.Due to the growing population, inevitable electricity needs,and negligence from the country’s policy makers, the powerinfrastructure in Layyah is facing adverse stress to providereliable, continuous, and quality services to the consumers.On the brighter side, the considered district holds the mostfavourable climatic conditions because sun shines for longerduration and there are extremely low chances of cloudy orrainy weather throughout the year implying maximumpotential for solar energy. In the first part of the research,the whole grid station of Layyah including three zones con-sisting of 24 distribution transformers each is simulated on

an Electrical Transient Analysis Program (ETAP) power flowsolver using the Newton-Raphson algorithm. The Newton-Raphson method provides a fast load flow solution withoutcomputing the superior order of derivatives for solving thesmall-, medium-, and large-scale distribution system andgives efficient results for computational cost minimization[20, 21]. Moreover, the results from the Newton-Raphsonmethod are more reliable with a higher success rate ofconvergence as compared to those from the other powerflow algorithms [22]. In this regard, the ETAP softwareis excellent for system planning and it has a positive effecton the test feeder so it can be employed for optimum sizeand location of DG in the substation [23]. Simulationresults performed on this platform reliably predict thesuperiority and effectiveness of the proposed methods[24]. The network layout, component ratings, and all oper-ating values considered in the simulation are based on theactual data of the region [25].

As a result of the computation, certain overloadedtransformers and distribution lines of the existing networkare identified causing load shedding, voltage deterioration,enhanced losses, and low power factor. In the second partof the research, the simulated power network of Layyah isupgraded to a DG network by the installation of distrib-uted solar power plants of 1MW each at subsequent inter-vals along the 11 kV bus in all the zones of the gridstation. Moreover, the underrated transformers and distribu-tion lines are replaced with new higher rated components tocircumvent overloading and failure issues. As suggested bythe results, all components of the network operate under nor-mal loading conditions, and the voltage profile and powerfactor at each load side improved substantially with a consid-erable reduction in the losses across each transformer anddistribution line.

Figure 1 shows a single-line diagram of a 132 kV gridstation of Layyah in which three isolators (81-1, 82-1,and 83-1) at three legs leading to zones A-C are connectedto the main 132 kV bus. There is one current transformerspecified by symbol “E” which has two available currenttransformation ratios of 100/5 A and 200/5 A. Subse-quently, each leg has an SF-6-type circuit breaker andlightening arrestor (LA) followed by a primary distributiontransformer (132/11.5 kV) of 20/26 MVA rating. There isone more current transformer with transformation ratiosof 1600/5 A and 800/5 A followed by a potential trans-former (11500/35V).

The grid of 132 kV shown in Figure 1 splits into threeprimary distribution networks which are categorized intothree zones: zone A, zone B, and zone C. The schematicdiagram of the individual zone of the distribution networkis shown in Figure 2. Each zone consists of further two11.5 kV branches with each branch having 12 transformersconnected to it for secondary distribution to the con-sumers. In this way, each zone is fulfilling demand to 24regions of consumers. The simulation results of the exist-ing system indicate that there are 23 transformers and38 distribution lines in total which are overloaded andare represented by red colors. The voltage profile is foundout to be around 300V which is much smaller than the

2 International Journal of Photoenergy

nominal value of 380V. The power factor across all the zonesis fluctuating around 0.7, and there are considerable lossesacross the transformers and distribution lines. In the newdesigned system, firstly, these transformers and distributionlines are replaced by highly rated components. In the secondstep, eight solar plants (Suntech, monocrystalline) of 1MWpower each are connected to the grid such that each branchis assisted with four units as shown in Figure 2. Each solarplant consists of 80 cells in series and 80 cells in parallel witheach cell having the rating of 180W. After solving the newsystem, it is established that the voltage level returns toaround 380V with a power factor of unity in the system.All losses in the system also reduce considerably.

This paper is organized as follows. Section 2 deals withcurrent and future trends of electricity needs, power genera-tion, annual demand factor, and power losses in the wholecountry. Section 3 discusses the Newton-Raphson powerflow algorithm. In Section 4, the implementations of theexisting system and new system are described in detail alongwith the discussion of results. Finally, conclusions are drawnin Section 5.

2. Current and Future Trends in Pakistan

In Pakistan, National Transmission & Despatch Company(NTDC) has designed a future load forecasting from 2017to 2040 in which installed capacity and peak demands arehighlighted at the end of each year. Although installedcapacity was more than the total demand of electricityeven in the past, the shortage of electricity is due to highlosses and plants not running at full capacity. In 2017,the installed capacity was 137328GWh, but the demandwas 25717MW. Future generation capacity and peakdemand are shown in Figure 3. In 2040, the total installedcapacity will reach 630529GWh and the peak demand willreach up to 110736MW [27]. Pakistan cannot fulfil itspeak demand because most of the generating power plantsare not running at rated capacity causing shortage ofpower in each state. The Quaid-e-Azam solar power planthas been installed in Bahawalpur, Pakistan, which has1000MW generation capacity but 400MW is in operationand 600MW is under progress. Some more projectsincluding hydro and renewable energy sources like solar,wind, biomass, and geothermal energy sources are underdiscussion for the expansion.

The demand factor of load varies from month to monthdepending on the daily activities of the population and theseason. In the month of February, it has a minimum valueof 0.58. The maximum demand is unity in the month of Junesince it is the hottest working month of the year before sum-mer vacations in institutes [27]. A month-wise graph of thedemand factor is shown in Figure 4.

In Pakistan, transmission and distribution losses varyfrom year to year which are plotted in Figure 5 from theactual data taken from NTDC [28]. The transmission anddistribution in Pakistan are not yet reliable which can beobserved from the data taken from the fiscal years 1981 to2018. In 1981, losses were 29.5% which were reduced to someextent after every year [28]. In 2017, the lowest losses of19.4% were recorded in the system which again surged to20% in 2018.

At the proposed site, power generation is less and powerconsumption is more due to which the system has increasedlosses, load fluctuations, and higher possibility of instrumentinterruption. A case study has been taken for solving theproblem of load shedding, active and reactive losses, andlow power factor and for improving the voltage profile. Thedata has been taken from the 132 kV grid station at Layyah,Pakistan. There is a problem of load shedding and a lowpower factor which has a minimum value of 0.69 and anaverage value of 0.84 in all the three zones. Minimum farend consumers’ voltage is 283V which is very less than the

81–1 82–1 83–1

Grid

132 kV

100,200/5 ALEH-81AEG (SF-6)

100,200/5 ALEH-82AEG (SF-6)

100,200/5 ALEH-83CHINA (SF-6)

E

E E E

E E

LA LA LA

LALALA

T-1 = 20/26 MVA132/11.5 kV(PEL)20/12/12

T-2 = 20/26 MVA132/11.5 kV(HEC)30/02/08

T-3 = 20/26 MVA132/11.5 kV(Elprom)01/02/18

1600,800/5 A 800, 1600/5 A 800, 1600/5 A

P.T P.T P.T11500/35 V 11500/35 V 11500/35 V

Incoming

11.5 kV 11.5 kV 11.5 kV

To zone A To zone B To zone C

IncomingIncoming

Figure 1: 132 kV grid station installed at Layyah, Pakistan [26].

Load 12Load 2Load 1

Load 13 Load 14 Load 24

11.5

kV

11.5

kV

11.5 kV/220 V

Sola

r cel

ls

Zones A, B, C

& co

nver

tor

Figure 2: DG in different zones with overloaded transformers anddistribution lines.

3International Journal of Photoenergy

transmitted value of 380V. There was also a deficit of 24MWpower compared to the total demand at the grid. There arethree zones in the 132 kV grid where each zone has an almost8MW energy deficit. So consumer energy demand cannot befulfilled, and daily 6- to 8-hour load shedding is a routine.

To solve this problem, two techniques are valuable: thefirst one is to inject a DG to the load side and the second isthat the grid station should be upgraded to 220 kV whichnecessitates higher upgradation cost. Here, DG injectioncan solve this issue with minimal cost and flexibility in thechoice of the installation venue. The ETAP software is usedto simulate the existing system and the new system. The oldsystem has more losses than the new system. Power deficitis also removed by injection of the solar system which has atotal of 24MW rated output in which each unit has 1MWgeneration capacity.

3. Power Flow Analysis

Power flow studies are of paramount importance for powersystem planning and upgradation and for determining thebest operation of existing systems. The power flow problemcan be solved by considering the admittance matrices of thenetwork incorporating all the buses and feeders using asingle-line diagram. All the buses are categorized as eithervoltage-controlled bus (or PV bus), load bus (or PQ bus)and slack bus (mostly bus 1). The Newton-Raphson methodbeing the most efficient method in all aspects is used for solv-ing power flow problems which also eliminates the need toexplicitly specify the slack bus. The Taylor series expansionup to two initial terms is the basis for solving a multivariablenonlinear equation in a polar form with equal number ofunknowns. The Newton-Raphson method is used for analy-sis of the 132 kV grid station at Layyah because of its conver-gence which is very fast and independent of size of buses, andlittle number of iterations is required for the solution of loadflow. The convergence process of the multivariable Newton-

204020352030Fiscal year

2025202020150

20

40

60

80

Peak

dem

and

(MW

) ×10

4

Pow

er g

ener

atio

n (G

Wh)

×10

4

100

0

20

40

60

80

100

Peak demand Power generation

Figure 3: Future load forecasting of the peak demand and installedcapacity.

0.5

July

Augu

stSe

ptem

ber

Oct

ober

Nov

embe

rD

ecem

ber

Janu

ary

Febr

uary

Mar

chAp

rilM

ayJu

ne

0.6

0.7

0.8

Dem

and

fact

or

0.9

1.0

Figure 4: Year-wise demand factor of load in Pakistan.

181980 1990 2000

Fiscal year2010 2020

20

22

24

26

Pow

er lo

sses

(%)

28

30

Figure 5: Power losses at transmission and distribution from 1981to 2018.

132 kV

Grid

Zone A

20 M

VA

20 M

VA

20 M

VA

Zone

A tr

ansfo

rmer

Zone

B tr

ansfo

rmer

Zone

C tr

ansfo

rmer

Zone B Zone C

Figure 6: Simulation diagram of a 132 kV grid connected to three20MVA transformers.


Raphson method is explained below.

Si = Pi + jQi =Vi 〠n

k=1Y∗ikV

∗k = 〠

n

k=1ViVkYike

j δi−δk−δikð Þ,

Pi = 〠n

k=1ViVkYik cos δi − δk − δikð Þ,

Qi = 〠n

k=1ViVkYik sin δi − δk − δikð Þ:

ð1Þ

Pi and Qi are the active and reactive powers, respectively.

f =Pi

Qi

" #,

x =δi

∣Vi∣

" #:

ð2Þ

When more variables are involved, f ′ is replaced by thepartial derivates of Pi and Qi with respect to the two entriesin column vector x. The resultant matrix f ′ shown in Equa-tion (3) is also called the Jacobian matrix.

f ′ =

∂Pi∂δi

∂Pi∂ ∣Vi ∣

∂Qi∂δi

∂Qi∂ ∣Vi ∣

26664

37775, ð3Þ

ΔPi

ΔQi

" #=

Pi schð Þ

Qi schð Þ

24

35 − Pi calð Þ

Qi calð Þ

24

35

= f ′Δδi

Δ∣Vi∣

" #,

ð4Þ

Δδi

Δ∣Vi∣

" #= f ′h i−1 ΔPi

ΔQi

" #: ð5Þ

The subscript cal denotes the calculated value and schrepresents the scheduled values. The iterative process stops

00

400

800

1200

1600

Tran

sform

er ra

ting

(kV

A) 2000

5 10 15 20Transformer #

250

5

10

15

20

25

Dist

ance

from

load

(km

)

(a)

00

400

800

1200

1600

Tran

sform

er ra

ting

(kV

A) 2000


250

5

10

15

Dist

ance

from

load

(km

)

20

25

(b)

00

400

800

1200

1600Tr

ansfo

rmer

ratin

g (k

VA

) 2000


250

5

10

15

Dist

ance

from

load

(km

)

20

25

(c)

Figure 7: Transformer ratings and route lengths in (a) zone A, (b) zone B, and (c) zone C.

Table 1: Specifications of the existing system.

Name of parameters Assumptions for parameter

System type Three-phase AC system

Type of distribution line Overhead line conductors

Type of load Constant load

Standard frequency 50Hz

Standard voltage 380V (L-L)

Type of conductorsAluminium conductorsteel reinforced (ASCR)

Voltage limits

Critical over voltage > 105%,critical under voltage < 95%,marginal over voltage > 102%,marginal under voltage < 97

Bus 1 Reference bus or slack bus


when the mismatches become smaller than the specifiedtolerance ϵ, i.e.,

ΔPi

ΔQi

" #≤ ϵ: ð6Þ

It should be noted that the entries in the calculationprocess exclude the slack bus so there will be n − 1 busesfor which the computation will be carried out.

4. Results and Discussion

A case study of the 132 kV grid station at Layyah has beensimulated on ETAP. The grid station is divided into threezones, namely, zone A, zone B, and zone C. At the distribu-tion level, 72 distribution transformers are connected to theload. There are 24 transformers in each zone and a mainpower transformer connected to the grid having the ratingof 20MW. After simulating the system, it appears that afew transformers are overloaded which can be observed fromtheir highlighted red color in the simulation in Figure 6. Thethree main transformers of zone A, zone B, and zone C arealso overloaded. In addition, the loads are located at suffi-

ciently large distance from the transformers. As a result, thesystem has transmission line losses, low power factor, andpoor voltage regulation due to overloading which are themain issues in the grid. In particular, during the peak hours,the power demand is higher than the generation, so the over-all system is not healthy to fulfil power demands to the con-sumers. The ratings of all transformers along with theirdistance from the load side in the three zones are plotted inFigure 7.

4.1. Existing System Implementation on ETAP. In order toanalyze the power flow of the three zones, implementationof the grid is done on the ETAP software. The specificationsof the existing system are shown in Table 1, and the same areconsidered in the simulation settings.

A 132 kV grid is implemented on the ETAP softwarewhose layout is shown in Figures 6 and 8–10. When the pro-gram runs on ETAP, the following results are obtained. Thethree main transformers of individual zones having ratingsof 20MVA each are overloaded as shown in Figure 6 by theirred colors. Moreover, in zone A, 11 transformers are over-loaded which are connected to the sugar mill colony, theemployees’ colony, Noorabad, Chandiawala, the Q.H.scheme, the lawyers’ colony, Qadeerabad, Laskaniwala,

Zone A

L1

L27 L47

L28

L26

L25

11.5

kV

800

kVA

400

kVA

1200

kVA

300

kVA

1200

kVA

1600

kVA

750

kVA

800

kVA

950

kVA

300

kVA

600

kVA

431

kW

642

kW

665

kW

707

kW

972

kW

253

kW

842

kW

560

kW

628

kW

932

kW

278

kW

800

kW

L48

296

V

293

V

296

V

320

V

306

V

304

V

314

V

Din

pur

Tibb

i khu

rdN

ashe

eb

Qad

eera

bed

Koro

nas

heeb

312

V

321

V

317

V

297

V

321

V

Shah

pur

�al

Mau

j gar

h

Sirg

ani t

hal

Shan

iwal

a

Moc

hiw

ala

Kach

iBh

arsh

ah

Lask

aniw

ala

Karo

r tha

l

300

V

Law

yers

'co

lony

Q.H

. sch

eme

Chan

diaw

ala

Basti

shee

kJa

lu

Noo

raba

d

TDA

colo

ny

Man

di to

wn

Empl

oyee

s'co

lony

Hou

sing

colo

ny

Man

zoor

abad

Cana

lco

lony

Suga

r mill

colo

ny

305

V

305

V

311

V

325

V

326

V

302

V

309

V

310

V

310

V

315

V

320

V

456

kW

242

kW

728

kW

515

kW

498

kW

1012

kW

806

kW

838

kW

258

kW

L4L2 851

kW

319

kW

664

kW 130

0 kV

A

800

kVA

200

kVA

1200

kVA

1000

kVA

750

kVA

1000

kVA

300

kVA

1500

kVA

1000

kVA

800

kVA

750

kVA

500

kVA

L3 L23

L24

Load 1 Load 2 Load 3 Load 4 Load 5 Load 6 Load 7 Load 8 Load 9 Load 10 Load 11 Load 12


650 k

VA

330 k

VA

1030

kVA

800 k

VA

770 k

VA

1600

kVA

1300

kVA

1300

kVA

1200

kVA

400 k

VA

850 k

VA

300 k

VA

850 k

VA

200 k

VA

1200

kVA

1000

kVA

750 k

VA

1100

kVA

1000

kVA

880 k

VA

800 k

VA

550 k

VA

500 k

VA

500 k

VA

Figure 8: Implementation of zone A of the existing system on ETAP.


Sirgani Thal, Maujgarh, and Shahpur Thal. In zone A, 18 dis-tribution lines are overloaded which are L1, L9, L10, L15,L16, L20, L21, L22, L23, L24, L36, L41, L43, L44, L45, L46,L47, and L48. For the sake of saving space, numbers are onlymentioned for the first four and last two lines. The marginallyand fully overloaded transformers are shown in pink and redcolors, respectively, and the overloaded distribution lines areshown in red colors in Figure 8.

In zone B, eight transformers and twelve lines are over-loaded. The overloaded transformers are connected toLohachthal, Zard, Jhoralnashib, Jakharpacca, Kharal Azeem,Khokharwala, Rakh, and Shahwala. Lines which are over-loaded include L59, L83, L84, L86, L88, L90, L91, L92, L93,L94, L95, and L96.

Finally, in zone C, four transformers are overloaded.These transformers are connected to Saeed Nasheeb, Lad-hana, Jamanshah, and Awanwala. There are eight lines whichare overloaded. These distribution lines are L97, L109, L131,

L132, L133, L139, L140, and L142. As a result of overloading,there is an observed deficit of 24MW resulting into 6 to 8hours of load shedding every day.

4.2. New Design of the 132 kV Grid Station. At the distribu-tion side, solar cell modules are installed at uniform intervalsafter each third distribution line to overcome the problems ofpower shortage, voltage regulation, and low power factor.There is a deficit of 8MW in each zone, so eight solar panelsof 1MW rating each are installed in each zone. The solarpanel is installed at the distribution end or close to the userend to balance deficit and reduce line losses. The single-linediagram of the grid and all the three zones of the new systemare shown in Figures 11–14, respectively.

After the installation of distributed solar panels in eachzone, considerable power is extracted from the DG sets whichcauses less burden on each zonal transformer (20MVA).Hence, all three zonal transformers return to their normal

500

kVA

250

kVA

1000

kVA

1000

kVA

800

kVA

660

kVA

1400

kVA

750

kVA

800

kVA

1200

kVA

200

kVA

400

kVA



0 kVA

200 k

VA

1200

kVA

800 k

VA

750 k

VA

1400

kVA

600 k

VA

800 k

VA

1000

kVA

1000

kVA

250 k

VA

500 k

VA73

1 kW

324

kW

1028

kW

376

kW

937

kW

1193

kW

1229

kW

614

kW

578

kW

838

kW

222

kW

465

kW

L71

11.5 kV

Zone B

L49

L73

L75 L95

L51L5

2

L72

750

kVA

545

kW32

0 V

323

V

316

V

320

V

332

V

328

V

335

V

340

V

326

V

336

V

342

V

330

VG

ochi

Gad

di

Bait

Was

saw

a

Balo

ch k

han

Chaj

ra

Jakh

arpa

cca

Jhor

alna

shib

Kha

nwal

a

Rakh

Shah

wal

a

Kho

khar

wal

a

Kha

ral a

zeem

L96

285

kW

822

kW

569

kW

1222

kW

302

kW

966

kW

671

kW

316

kW

1034

kW

L76

L74 36

0 kW

1360

kW 40

0 kV

A

1100

kVA

700

kVA

1600

kVA

350

kVA

1200

kVA

900

kVA

250

kVA

1300

kVA

350

kVA

1200

kVA

L50

299

V

283

V

318

V

321

V

321

V

323

V

Jhor

alth

al

340

V

320

V

347

V

333

V

319

V

335

V

Am

ircla

sra

Pana

hK

hara

l

Pirja

gi

Was

aya

Soha

nra

Sohi

atha

l

Shar

if A

raye

n

Dub

ali

Loha

chth

al

Weh

niw

alth

al

Karlo

Zard

800 k

VA

440 k

VA

1200

kVA

750 k

VA

1600

kVA

380 k

VA

1300

kVA

900 k

VA

250 k

VA

1300

kVA

350 k

VA

1200

kVA

Figure 9: Implementation of zone B of the existing system on ETAP.


operating regimes despite having the same power rating asbefore. In addition, the overloaded transformers and distri-bution lines are replaced with higher rating componentsdue to which their overloading problems are also eliminated.These facts can be observed from Figures 12–14 for zone A,

zone B, and zone C, respectively. Finally, all the problemsof low power factor, voltage regulation, and power losses intransformers and transmission lines occurring in the systemare resolved. The comparison of results between the existingsystem and the new simulated system is done in the nextsection.

4.3. Zone A: Transformer, Distribution Lines, and LoadAnalysis. In zone A of the existing system, 11 transformersare overloaded. Due to the overloaded transformers, the sys-tem is unbalanced. To overcome this problem, new trans-formers of higher rating are connected to replace the oldones and avoid overheating of transformers. As a result, thesystem reliability is increased and transformer losses are alsoreduced. A comparison between old and new ratings isshown in Figure 15.

DG at the load side has reduced losses to a great extent. Ithas increased cost for replacing new transformers but ful-filled the demand of customers. Transformer losses reachup to 18 kW in the old case which remain below 6kW forthe DG-injected system. Losses across each transformer inthe old system and the new system are plotted inFigure 16(a).

Zone C

L123 L143Load 49

800 k

VA

400 k

VA

400 k

VA

1100

kVA

1200

kVA

1200

kVA

1000

kVA

800 k

VA

800 k

VA

1200

kVA

330 k

VA

550 k

VA

1700

kVA

500 k

VA

1000

kVA

700 k

VA

1300

kVA

800 k

VA

380 k

VA

1800

kVA

800 k

VA

1300

kVA

450 k

VA

650 k

VA

Load 50 Load 51 Load 52 Load 53 Load 54 Load 55 Load 56 Load 57 Load 58 Load 59 Load 60


L97

11.5

kV

1700

kVA

�al

kala

n

�al

jand

i

Baitd

ewan

Jam

rid

Jam

ansh

ah

Basti

nano

Sum

rans

hib

Shad

okha

n

Kapb

ali

Awan

wal

a

337

V

319

V

333

V

338

V

334

V

316

V

322

V

322

V

313

V

311

V

315

V

305

V

Jaisa

lnas

eeb

Mad

niTo

wn

500

kVA

1000

kVA

700

kVA

1300

kVA

800

kVA

350

kVA

1800

kVA

800

kVA

1300

kVA

450

kVA

600

kVA

L121

L122

L124 650

kW

1040

kW

359

kW

696

kW

911

kW

311

kW

1219

kW

568

kW

445

kW

258

kW

L144

852

kW

1463

kW

800

kVA

400

kVA

400

kVA

1100

kVA

1200

kVA

1200

kVA

1200

kVA

300

kVA

500

kVA

1000

kVA

800

kVA

800

kVA

L98

L100

Bairo

onKu

nal

333

V

330

V

340

V

340

V

324

V

321

V

307

V

316

V

313

V

Loha

ncht

hal

310

V

305

V

298

V

Saee

dN

ashe

eb

Ladh

ana

Loha

nchw

ala

Mirr

anip

acca

Nag

gilo

hanc

h

Said

otha

l

Kotla

qazi

Sam

tiath

al

Gut

thal

Kunn

alna

shib72

8 kW

351

kW

1107

kW

356

kW

948

kW

922

kW

1107

kW

581k

W

558

kW

800

kW

246

kW

L120

456

kW

L99 L119

Figure 10: Implementation of zone C of the existing system on ETAP.

132 kV

Grid

Zone A

20 M

VA

20 M

VA

20 M

VA

Zone

A tr

ansfo

rmer

Zone

B tr

ansfo

rmer

Zone

C tr

ansfo

rmer

Zone B Zone C

Figure 11: Simulation diagram of a 132 kV grid after DG injection.


Lines losses are also reduced when DG is injected to theload side by replacing lines with proper ratings. The existing17 distribution lines having the capacity of 267MW are over-loaded, and they are replaced with new lines with a rating of500MW. Line losses reach up to 110 kW in the existing sys-tem which remain below 11kW for the proposed system. Agraph is shown in Figure 16(b) which compares line lossesin the old and new systems.

The power factor of load is improved when DG isinjected at the load side. So the new power factor is slightlyless than unity which is a good sign for a robust power sys-tem. A high power factor also reduces the cost of equipmentbecause equipment cost under a low power factor is high dueto high current ratings. A high power factor reduces the cop-per losses because the phase component of the current isreduced. It has also decreased the losses and voltage regula-tion which were occurring due to the low power factor. Thegraph of power factors and voltage profiles at the load sidefor zone A is shown in Figures 17(a) and 17(b).

The power factor for specific loads is better (>0.9) in theexisting system; however, it stays below 0.85 for most of theconnected loads. In the simulated system, the power factorhas improved drastically to around unity. Voltage, on theother hand, has sufficiently small values at the load sidewhich vary mostly between 300V and 320V. The desiredvalue of voltage is 380V (3 −Φ line-to-line voltage) whichis successfully achieved by photovoltaic installation.

4.4. Zone B: Transformer, Distribution Lines, and LoadAnalysis. Zone B consists of 24 transformers, 24 loads, and48 lines. In the existing system, 4 transformers are overloadedrequiring new transformers of better ratings to be installed. Acomparison between old and new ratings is shown inFigure 18.

After replacing old transformers with those of better rat-ings, losses are reduced considerably as in the previous case.Transformer losses which were reaching 38 kW are nowreduced to smaller values with maximum approaching

Zone C

1000

kVA

500 k

VA

1500

kVA

500 k

VA

1500

kVA

1500

kVA

2000

kVA

1000

kVA

1000

kVA

1500

kVA

500 k

VA

1000

kVA

1500

kVA

500 k

VA

1500

kVA

1000

kVA

1000

kVA

1500

kVA

500 k

VA

2000

kVA

1000

kVA

1500

kVA

1500

kVA

1000

kVA



11.5 kVSu

gar m

illco

lony

Cana

l col

ony

Man

zoor

abad

Hou

sing

colo

ny

Empl

oyee

s'co

lony

378

V37

8 V

378

V

377

V

377

V

377

V

375

V

375

V

374

V

374

V

374

V96

8 kW

1453

kW

1454

kW

971

kW

1948

kW

488

kW

1473

kW

977

kW

982

kW

1483

kW

493

kW

1492

kW1

500

kVA

1500

kVA

1000

kVA

1000

kVA

1500

kVA

500

kVA

2000

kVA

1000

kVA

1500

kVA

1500

kVA

1000

kVA

Shah

pur �

al

Mau

jgar

h

Sirg

ani �

al

Karo

r �al

Shan

iwal

a

Moc

hiw

ala

Lask

aniw

ala

Kach

iBa

hars

hah

Din

pur

Koro

Nas

heeb

Tibb

i Khu

rdN

ashe

eb

Qad

eera

bad

500

kVA

376

V

379

V

378

V

379

V

375

V

377

V

377

V

375

V

375

V

376

V

376

V

376

V

375

V

Man

di T

own

TDA

colo

ny

Noo

raba

d

Basti

She

ekJa

lu

Chan

diaw

ala

Q.H

. sch

eme

Law

yers

'co

lony

987

kW

494

kW

1488

kW

485

kW

1469

kW

1471

kW

1949

kW

977

kW

976

kW

1457

kW

488

kW

973

kW100

0 kV

A

500

kVA

1500

kVA

500

kVA

1500

kVA

1500

kVA

2000

kVA

1000

kVA

1000

kVA

1500

kVA

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

500

kVA

1000

kVA

Figure 12: Implementation of zone A of the new system on ETAP.


11 kW. Old transformer losses and new transformer lossesfor zone B are plotted in Figure 19(a).

Line losses are also reduced after the installation of DGand by replacing distribution lines of proper ratings. Sevendistribution lines (267 A) are overloaded and are replacedwith 500 A lines. Consequently, line losses reduce and staybelow 12kW which were approaching 120 kW in the existingsystem. A graph is shown in Figure 19(a) that compares oldsystem line losses and new system line losses.

The power factor of load is improved when DG isinjected at the load side. So the new power factor is close tounity as in the previous case. It also reduces the losses andimproves voltage regulation. The power factor in the old sys-

tem fluctuates and reaches up to a minimum of 0.73 which isimproved to around unity with DG injection. The voltagealso stays below 350V; however, it stays higher than 375Vfor the new system. The graphs of the power factor and volt-age profiles are shown in Figures 20(a) and 20(b),respectively.

4.5. Zone C: Transformer, Distribution Lines, and LoadAnalysis. Zone C consists of 24 transformers, 24 loads, and48 lines. In the existing system, 8 transformers are over-loaded. To overcome this problem, new transformers areconnected to the load. A comparison between old and newratings for zone C is shown in Figure 21.

Load 25 Load 26 Load 27 Load 28 Load 29 Load 30 Load 31

11.5 kV

11.5 kV

Zone B

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

Load 32 Load 33 Load 34 Load 35 Load 36


2000

kVA

500 k

VA

2000

kVA

1000

kVA

500 k

VA

1500

kVA

1000

kVA

1500

kVA

1500

kVA

1000

kVA

500 k

VA

500 k

VA

1000

kVA

500 k

VA

1000

kVA

1000

kVA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1000

kVA

1500

kVA

1000

kVA

379

V37

6 V

376

V

377

V

377

V

377

V

376

V

377

V

375

V

375

V

375

V

377

V

374

V

378

V

378

V

378

V

377

V

377

V

377

V

374

V

376

V

375

V

375

V

375

V

2000

kVA

500

kVA

1500

kVA

1000

kVA

1500

kVA

500

kVA

500

kVA

1500

kVA

1000

kVA

1000

kVA

2000

kVA

500

kVA

1000

kVA

500

kVA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1000

kVA

1000

kVA

1000

kVA

1000

kVA

1985

kW

494

kW

494

kW

981

kW

1473

kW

490

kW

1924

kW

972

kW

1458

kW

488

kW

975

kW

1480

kW

981

kW

490

kW

1472

kW

930

kW

1473

kW

1468

kW

1473

kW

973

kW

972

kW

1473

kW

1480

kW

967

kW

Gad

di

Balo

ch K

han

Bait

Was

awa

Kha

nwal

a

jhor

alna

shib

Jakh

arpa

cca

Chaj

ra

Kha

ral A

zeem

Kho

khar

wal

a

Rakh

Shah

wal

a

Goc

hiA

mir

Clas

ra

Pana

h kh

aral

Pirja

gi

Shar

if A

raye

n

Soha

nra

Was

aya

Sohi

atha

l

Jhor

alth

al

Weh

niw

alth

al

Loha

chth

al

Dub

ali

Karlo

Zard

Figure 13: Implementation of zone B of the new system on ETAP.


When transformers of proper ratings are used, lossesreduce to a great extent. In the old system, transformer losseswere reaching 30 kW and they reach up to 6.5 kW for the newsystem. The graph of transformer losses is shown inFigure 22(a).

Line losses are reduced when DG is injected and byreplacing lines of proper ratings. Twelve distribution linesare overloaded and are replaced with 500MW lines in thesystem. In zone C too, line losses are approaching 120 kWwhich reduces to around 6 kW for the new system. A graphis shown in Figure 22(b) showing the line losses in the exist-ing and updated systems. The power factor of the load isimproved when DG is injected at the load side. Again forzone C, the new power factor is nearly unity. For the existingsystem, the power factor reduced to as low as 0.68 whichimproved after the DG injection. The graph between oldand new power factors is shown in Figure 23(a).

The voltage profile is also improved as a result of DGinjection. For the old system, the voltage level varied between

11.5

kV

Zone C

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W

1 M

W


Load 61

2000

kVA

2000

kVA

500 k

VA

2000

kVA

1000

kVA

500 k

VA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1000

kVA

500 k

VA

1000

kVA

1000

kVA

500 k

VA

1000

kVA

1000

kVA

2000

kVA

1500

kVA

1500

kVA

1500

kVA

1500

kVA

1000

kVA

500 k

VA

500 k

VA

500

kVA

1985

kW

495

kW

1484

kW

975

kW

1470

kW

1474

kW

490

kW

1952

kW

971

kW

1456

kW

489

kW

970

kW

379

V

378

V37

9 V

378

V37

9 V

378

V

377

V

377

V

377

V

377

V

376

V

376

V

375

V

375

V

375

V

376

V

374

V

377

V

377

V

376

V

376

V

375

V

375

V

375

V

1500

kVA

1500

kVA

1500

kVA

500

kVA

500

kVA

1500

kVA

1000

kVA

1000

kVA

2000

kVA

1000

kVA

1000

kVA

500

kVA

1500

kVA

1500

kVA

1500

kVA

2000

kVA

500

kVA

1500

kVA

1000

kVA

1000

kVA

1000

kVA

500

kVA

Load 62 Load 63 Load 64 Load 65 Load 66 Load 67 Load 68 Load 69 Load 70 Load 71 Load 72

968

kW

488

kW

1459

kW

970

kW

971

kW

1951

kW

1468

kW

1471

kW

470

kW

492

kW

993

kW

1476

kW

�al

kala

n

Bairo

onku

nal

Gut

thal

Kunn

alna

shib

Loha

nchw

ala

Mirr

anip

acca

Nag

gilo

hanc

h

Said

otha

l

Kotla

qazi

Sam

tiath

al

Loha

ncht

hal

Saee

dN

ashe

eb

Ladh

ana

Mad

ni T

own

�al

jand

i

Baitd

ewan

Jam

rid

Jaisa

lnas

eeb

Jam

ansh

ah

Basti

nano

Sum

rana

shib

Shad

okha

n

Kapb

li

Awan

wal

a

Figure 14: Implementation of zone C of the new system on ETAP.

00

500

1000

1500

Tran

sform

er ra

ting

(kVA

)

2000

2500

5 10 15Total no. of transformers

20 25

Actual ratingNew rating

Figure 15: Actual and new rating of transformers in zone A.


300V and 340V which improved substantially to around378V after photovoltaic injection. Old and new voltage levelsare shown in Figure 23(b).

5. Conclusion

Pakistan is an underdeveloped country where energy crisesare more and the overall economy is low. A case study has

been taken to observe load flow from the 132 kV grid stationat Layyah. There are issues of power losses, poor voltage pro-file, low power factor, and overloaded transformers. To solvethese issues, two techniques are available: one is to upgradethe grid to 220 kV and the other is to inject a DG system tofulfil the needs of the demand side. The second approach isadopted for the solution of problems. Three zones weredesigned on ETAP to simulate a power flow algorithm usingthe Newton-Raphson method and discussed one by one.Each zone consists of 24 transformers, 24 constant loads,and 48 cables.

Zone A has 24 transformers in which 11 transformers areoverloaded and 18 distribution lines are overloaded. The loadpower factor is 0.71 at Shahpur Thal, and the lower voltage atMaujgarh was 293V. When DG is injected in all trans-formers, distribution lines started working properly withminimum losses. Shahpur Thal’s load power factor becomes0.9975, and Maujgarh’s voltage profile is improved from293V to 374V. Similarly, losses reduced in every element,and also the power factor improvement is noticeable. ZoneB has 24 transformers in which 8 transformers are over-loaded, 12 distribution lines are overloaded, and the lowestpower factor is 0.69 at Awanwala. The lowest voltage at Lad-hana is 298V. When DG is injected to all transformers, dis-tribution lines started working in a proper way withminimum losses. Awanwala’s power factor of loads became0.9973. Ladhana’s voltage profile improved from 298V to

25Total no. of transformers

20151050

25

20

Tran

sform

er lo

sses

(kW

)

15

10

5

0

A�er DG injectionExisting system

(a)

50

A�er DG injection

Total no. of lines403020100

Line

loss

es (k

W)

0

30

60

90

120

Existing system

(b)

Figure 16: (a) Transformer losses and (b) line losses before and after DG in zone A.

00.6

0.7

0.8

Load

pow

er fa

ctor

0.9

1.0

5 10 15 20 25Total no. of loads


(a)

VR (

V)

0280300320340360380400



(b)

Figure 17: (a) Power factor and (b) voltage at the receiving end in zone A.

00

500

1000

1500

Tran

sform

er ra

ting

(kVA

)

2000

2500


20 25


Figure 18: Actual and new rating of transformers in zone B.


374V. Zone C has 24 transformers in which 4 transformersare overloaded, 8 distributions lines are overloaded, and thelowest power factor is 0.75 at Zard. The lowest voltage atKarlo is 283V. When DG is injected, distribution linesstarted working properly with minimum losses. The powerfactor of loads in the Zard region becomes 0.9862. The volt-age profile in the Karlo region improved from 283V to

375V. Initially, total losses were 4.58MW and 12.30MVARwhich were then reduced in the newly implemented systemup to 0.548MW and 0.834MVAR. Load forecasting is donein this case study where more power is needed. In this design,old transformers were replaced by new transformers to savethe consumer side from outages of power. Every zone needs8MW power, so 24 solar panels of 1MW each were installedat the consumer side. This method has the potential to over-come the problem of load shedding as well, which is about 6to 8 hours in the region.

Data Availability

The data used to support the findings of this study areincluded within the article. The data is cited at relevant placeswithin the text as references.

Conflicts of Interest

The authors declare that there is no conflict of interestregarding the publication of this paper.

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20151050

Tran

sform

er lo

sses

(kW

)

0

10

20

30

40


(a)

50

A�er DG injection


Line

loss

es (k

W)

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90

120

150

Existing system

(b)

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060

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(a)

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Figure 23: (a) Power factor and (b) voltage at the receiving end inzone C.


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https://nepra.org.pk/Legislation/2-Rules/2.7%20NEPRA%20Performance%20Standards%20(Transmission)%20Rules,%202005/Performance%20Standards%20(Transmission)%20Rules%202005.pdfhttps://nepra.org.pk/Legislation/2-Rules/2.7%20NEPRA%20Performance%20Standards%20(Transmission)%20Rules,%202005/Performance%20Standards%20(Transmission)%20Rules%202005.pdfhttps://nepra.org.pk/Legislation/2-Rules/2.7%20NEPRA%20Performance%20Standards%20(Transmission)%20Rules,%202005/Performance%20Standards%20(Transmission)%20Rules%202005.pdfhttps://nepra.org.pk/Legislation/2-Rules/2.7%20NEPRA%20Performance%20Standards%20(Transmission)%20Rules,%202005/Performance%20Standards%20(Transmission)%20Rules%202005.pdfhttp://www.emco.com.pk/index.php/about-emco/our-projects/132kv-projectshttp://www.emco.com.pk/index.php/about-emco/our-projects/132kv-projects

Implementation of Distributed Generation with Solar Plants in a 132 kV Grid Station at Layyah Using ETAP1. Introduction2. Current and Future Trends in Pakistan3. Power Flow Analysis4. Results and Discussion4.1. Existing System Implementation on ETAP4.2. New Design of the 132 kV Grid Station4.3. Zone A: Transformer, Distribution Lines, and Load Analysis4.4. Zone B: Transformer, Distribution Lines, and Load Analysis4.5. Zone C: Transformer, Distribution Lines, and Load Analysis

5. ConclusionData AvailabilityConflicts of Interest

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Implementation of Distributed Generation with Solar Plants in a 132kV … · 2020. 6. 25. · Research Article Implementation of Distributed Generation with Solar Plants in a 132kV